Louis Joseph Gay-Lussac was a French Enlightenment chemist and physicist born on December 6, 1778. He is known for the formulation of the gas law and also studied magnetism.

Gay-Lussac dropped out of Engineering to pursue chemical research. It was supported by two great philosophers of the time, Berthollet and Laplace. He was Professor of Sorbornne Physics and Chemistry at the Polytechnic School. In 1797, he entered the Polytechnic School in Paris and graduated in 1800.

In 1802, he demonstrated his first work, which was on the expansion of gases. It was the first to formulate the second gas law. Today this law is called the Charles and Gay-Lussac Law or simply the Gay-Lussac Law.

It also developed the Volumetric Law. His thesis was published in 1808 and involved the reaction between oxygen and hydrogen. It was from this experience that his name came to be used as a unit for measuring alcohol volume. This unit measures the alcohol content of beverages. It is usually expressed in degrees, so Gay-Lussac degrees are used.

In 1804, his passion for research made him fly in a balloon at almost 4,000 meters in order to study variations in temperature, pressure and also the composition of the atmosphere at high altitudes. Not very successful in research, but his ride was a record balloon flight due to his altitude, which was only surpassed in the following century.

In 1805, he traveled to Italy on an expedition with Humboldt and then interned at his laboratory in Berlin, where they studied the volumetric ratio of hydrogen and oxygen to form water. He married in 1808, the same year he determined the precise volumetric composition of water with the help of scientist Alexander von Humboldt.

Made analyzes of substances present in plants and animals and studied the solubility of salts. In enacting the gas expansion law, Gay-Lussac clashed with British scientist John Dalton. Spread around the same time, Dalton's theory related weights rather than volumes. Later, the Italian physicist Amedeo Avogadro demonstrated how the results were reconciled.

He was elected a member of the Paris Academy of Sciences for his contribution to chemistry. He was also elected to the Royal Society of London, England. He wrote many notes, articles, works, and memoirs about his research. Gay-Lussac had an active political life and died in Paris on May 9, 1850.